Manyday was a monthly event that would originally take place in the Inner Ring and later in a separate area of the same name of the event every 19th day of the month, during the early years of Manyland. The celebratory day was chosen due to most Object Types on Manyland being 19x19 pixels in size.

The events eventually stopped occuring over time, but the tradition was revived in 19th of April, 2015, with the creation of the area "Manyday" and the Manyday event themed "Under the Sea". Events of a different theme occured this and every month after said event, between the 19th days of April, 2015, and March, 2016; all as a subarea of the area, and included creation and/or story contests that opened some time before the event, and competitive events in the area such as races. Each event often took place two times, in the morning and evening in Manyland Time.

As 2016 aged, motivation for the continuation of the monthly holiday decreased, and most events often either didn't happen, or happened with far less complexity or preparation. No Manyday events happened in 2017, although some were attempted with no turnout, and it continues to not occur as of 2018.